An optical bit rate converter is an important component for communication and computing systems such as ultra-high speed, time division multiplexed (TDM) multi-access networks. In TDM multi-access networks, the network bus may operate at a rate of 100 Gb/s. However, the data processing may be performed electronically. The electronic device receiving the ultra-high speed (on the order of 100 Gb/s) optical data stream will require a receiver node to buffer the incoming ultra-high speed optical data stream, rate convert the optical data to electronic rates (approximately 100 MHz-10 GHz), and detect and process the data. Optical bit rate converters are useful for rate-converting ultra-high speed optical data streams to lower rate optical data streams that can be detected and processed electronically.
One method for performing rate conversion known to the prior art is to demultiplex every K.sup.th bit of an N bit long optical data packet, K and N being relatively prime. As used herein, a set of numbers is "relatively prime" when the greatest common divisor of all the numbers in the set is equal to one. Further, as used herein, the term data pattern means the series of bits being converted and includes but is not limited to blocks and packets of data. The time required to rate convert an entire pattern of optical data using this demultiplexing method is substantially NKT.sub.b, where N is the length of the fundamental data pattern, K is an integer, and T.sub.b is the bit period (inverse of the bit rate) of the original optical data stream being rate-converted. This known demultiplexing method, with K.noteq.(mN+1), where m is a whole number, however, scrambles the data bits of the original optical data pattern and requires further processing to reconstruct the original data pattern. In another known demultiplexing method, in addition to scrambling bits, only certain bits of data are selected from the original optical data stream and the rest of the bits are ignored. This demultiplexing method does not maintain all the bits of the original optical data stream in the rate-converted data stream.
In general, known bit rate converters utilize electronic or electro-optic devices, such as electronic memory. The bandwidth of these electrical devices limits the data rate of the optical data streams which can be rate-converted.
What is desired then is a rate converter which converts ultra-high speed optical data streams to lower rate optical data streams. The present invention permits such functionality.